When hno3 and au are mixed together, what do you expect to happen, and why? a. no reaction, because au is above h on the activity series and they cannot react b. no reaction, because au is lower on the activity series and cannot replace h c. they form au(no3)2 and h2, because au is more reactive and able to replace h d. they form au(no3)2 and h2, because they trade places in a double replacement reaction

B. No reaction, because Au is lower on the activity series and cannot replace H

Explanation: A single displacement reaction is one in which a reactive element displaces a less reactive element from its salt solution.

As gold (Au) is less reactive than hydrogen and thus lies lower in reactivity series, it would not be able to displace hydrogen from . Thus there  will be no reaction.

no reaction

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.

practical process described pest part of scientific investigation.

because practical knowledge is powerful then therotical knowledge.